<html>
	<head>
		<title>Learn jquery</title>		
		<script type="text/javascript" src="jquery-1.6.1.js"></script>
	</head>
	<body>
		<input type='text' id='mytextbox' value='123' />
		<input type='button' id='dangnhap' value="Login" />
		<script>
		$(document).ready(function(){
			$("#dangnhap").click(function(){
        								
				var a = $('input[id=mytextbox]').val();
				alert(a);
				
			});//end click
		});
		</script>  
	</body>
</html>